Re: What are the PHD2 settings used in a Mach1?

Michael Fulbright <mike.fulbright@...>

Thanks for the suggestion I can give it a try next clear night.   I think I've played with both 0.5x and 1.0x over time and being predominately seeing limited (Mid-Atlantic can be cruel seeing-wise) I'd just settled on whatever I tried last!

Michael Fulbright

On 12/5/2017 3:34 PM, chris1011@... [ap-gto] wrote:

I use 0.5x for guide speed but I know 1.0x is known to work well also.
If you use .5x for guiding, then indeed you may have to add some Dec backlash because your reversal time is essentially doubled, and the effect of any backlash is basically doubled. Dec backlash setting other than zero is a potential source of oscillation, that is why i do not recommend using any. Rather than guiding at .5x, use 1x guiding to minimize Dec reversal time, and this will speed up your dither recovery time. The 1 X guide rate is very accurate and the mount will respond better at the sub-arc sec level.

The slower rates were included from the very first mounts we made for manual guiding with a cross-hair eyepiece. It was done because human eye-hand response delay is on the order of 1/2 to 1 second, and at the 1x rate would cause the guide star to move too far. However, modern electronics does not have such delay, and the mount can respond to millisecond move commands, unlike a human guider.

-----Original Message-----
From: Michael Fulbright mike.fulbright@... [ap-gto]
To: ap-gto
Sent: Tue, Dec 5, 2017 2:06 pm
Subject: Re: [ap-gto] What are the PHD2 settings used in a Mach1?

I've never using the Guiding Assistant.  Probably can't hurt but make
sure you understand the settings it chooses.  DEC backlash is usually
discouraged but my mount has a bit of it that I've been too lazy to
adjust out and I find the autotuning that PHD2 does for DEC backlash
timing seems to improve guiding and recovery time from dither moves. YMMV.

I played with the Predictive PEC but as expected with a good PEM curve
it does effectively nothing and would probably just muddle things.

Key is to make sure you use the calculator provided to get the
calibration move time correct.  It just needs guide focal length and
camera pixel size (microns).

I use 0.5x for guide speed but I know 1.0x is known to work well also.

It is really hard to mess this up with a nearly perfect mount like the
Mach1 unless you overdrive the mount or set the minimum move to
something stupid small like 0.1 arcsec.

Michael Fulbright

Posted by: Michael Fulbright <mike.fulbright@...>

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